safety exam

reagent reacts spontaneously with water (like P2O5 or alkali metals)

1. check for Perosides

2. pre dry over CaCl2 or KOH

3. fine dry + distillation over Na or NaH (bezophenone as indicator)

1. pre dry over CaCl2

2. fine dry + distillation over CaH2 or P2O5

   Do not use Na!

Distilation over Na

solw addition of EtOH or i-PrOH to a stirred and cooled mixture of the hydride in an inert organic solvent

NaH+R-OH -> RONa+ H2

Slow Addition of EtOAc to a solution of LiAlH4 in Et2O or THF followed by the addition of H2O

LiAlH4+ 2 EtOAc->->4 EtOH+LiOH+Al(OH)3

Slow addition of H2O to a solution of the borohydride in MeOH or EtOH

NaBH4+4H2O->NaB(OH)4+4H2

slow EtOH addition to a mixture of the reagent in an inert solvent (THF) until gas evolution stops

R-Li+EtOH-> R-H+EtOLi

No H2O!!

slow addition of small pieces in t-BuOH or i-PROH

everything has to dissolve

NA+t-BuOH->t-BuONa+1/2H2

danger of auto ignition upon drying

small amounts can be disposed with a big excess of water

lager amounts have to be collected

slow addition of diluted NaOH to the stirred and ice-cooled reagents

small amounts: addition of NH3 (10%)

lager amounts: killer solutions (10% ethanolamine, 30% diethyleneglycole-monobutylether and water)

CH3I+NH3->Mehtyl/Dimethylamine

Dispropotionation in NaOH

Cl2+2NaOH->NaCl+NaOCl+H2O

Reduction with Fe(II)-salts an acidic aqueous solution

ROOR+2Fe2+ + 4H+-> 2ROH+H2O+Fe3+

ROOH+2Fe2+ + 2H+-> ROH+H2O+2Fe3+

Oxidation with NaOCl

H2S+4NaOCl+2H2O->SO4(2-)+NaCl+2H3O+

small amounts: FeSO4-> Fe-Hexacyanoferrate (Berliner Blau)

large amounts: first hydrolyzedwith NaOH and then oxidized with H2O2

NaCN+H2O2+H2O->CO2+NH3+NaOH

yes

yes

no

no

no

no

no

no

no

yses

yes

yes

yes

no

no

no

no

yes

no

no

no

yes

yes

no

yes

n-O bonds

n-X bonds

N-N bonds (also double/triple bonds)

N-Metal

O-O bonds (peroxo-)

O-X bonds

react violently with water

can lead to explosion and fire

side by side storage -> serious hazard

examples: alkali metals, organometallic compounds, alkalimetalalkoxides/amides, metal hydrides, anhydrous (non) metal halides, oxides, inorganic acids/bases, (in)organic acid halides, organic acid anhydrides

C-metal bonds

C-C triplebonds

1. potassium, sodium and their amides; diisopropylether

2. rings and chains containing oxygen; double-/triplebonds

   those compounds are dissolve in a liquid. They become dangerous after concentration by distillation.

strong oxidizer/reductant - explosion

DMSO+HClO4 - explosion/fire

NH3/NAOCl/I2 - primary explosive

aqua regia - dissolves gold

Piranha solution - explodes spontaneously and dissolves flesh

1. synthesis of metal-organic reagents Mg/Zn + R-X(time delayed reaction)

2. nitrations (using nitrosulfonic acid

3. Oxidation/Epoxidation (using H2O2, CrO3, O3,…)

4. Reduction/deprotonation (using Na, K, LiAlH4)

5. Polymerization

   
   

surface volume ratio decreases dramatically

1. t-BuLithium, metal alkyls

2. raney nickel

3. metal dust

4. white phosphorous

5. B2H6, PH3, SiH4

treatment: inert conditions, special disposal or chemical destruction; prepare adequate fire extinguisher

1. HCN and inorganic cyanides (KCN)

2. HN3 and inorganic azides(NaN3)

3. Fluorine (F2), chlorine (Cl2), ozone (O3)

4. Hydrofluoric acid (HF)

5. Phosphoric acid esters

6. Phosgene (COCl2)

7. diborane (B2H6, phosphane (PH3)

NaN3+acid->HN3 very toxic/explosive

KCN+acid->HCN very toxic

Na2S+ acid->H2S very toxic

HCOOH+H2SO4 conc->CO toxic

NaOCl+acid->Cl2 toxic corrosive

Ca3P2+H2O->PH3very toxic pyrophoric

PCl3+H2O(small amount)->PH3+P2H4 very toxic pyrophoric

NaBH4+H2SO4 conc.->B2H6 very toxiv pyrophoric

acetone immediately

acetonitrile 1 min

acetic acid >480 min

chloroform immediately

dichloromethane immediately

diethylamine immediately

diethylether immediately

conclusion latex saftey gloves are unsuitable for organic synthesis